I'm no longer sending letters to supporters/donors. Instead encourage thee to send letter to thyself to prove thou knows thou is human, not person, and thou lives without United States, not within.
Send to "John of the Smiths" not John Smith
No abbreviations
No two-letter 'states' - as this actually means territories
Spell out every word
No zip code
Send a few. Use regular stamp.
Then use the letter to help prove who is thou is. Use the Certificate of Live Birth as well. Use a declaration. No need for driver's license/permission nor the port-pass. Let them try to prove otherwise.
Of course, thou should also rescind voter registration since that is for the territorial elections within United States (not The USofA). State citizens/nationals don't need to register for elections since just being state citizen gives one the right to vote. Yes, one must prove who thou is when voting, but thou does not need to register.